The present invention relates to an image forming apparatus such as a full-color copy machine or a color printer, and its control method (in particular, toner supply control).
In conventional xerographic image forming apparatuses using a laser, a dedicated sensor for sensing a toner residual amount in a developing unit is provided to maintain a constant amount of toner in the unit. This type of sensor is, for example, a magnetic sensor or an adhesion strength sensor, etc.
Japanese Patent Application KOKAI Publication No. 11-174909 discloses a technique for easily and accurately estimating the consumption of toner. This technique is characterized in that a correction amount is determined on the basis of an image type, a toner residual amount and humidity, and a time period in which a toner supply motor is kept in the ON state is calculated using a predetermined formula.
However, in the above case, a developing unit provided with a dedicated sensor inevitably increases the cost. In other words, the technique does not sufficiently satisfy the requirements of downsizing and cost reduction.
Even at present, there is a demand for accurate and easy estimation of toner supply timing, executed while satisfying the requirements of downsizing and cost reduction.
The present invention has been developed in light of the above, and aims to easily and accurately estimate toner supply timing by counting laser pulses when forming an image, calculating the consumption of toner in a developing unit on the basis of the counting result, and calculating a time period in which toner is to be supplied into the developing unit.
Additionally, the present invention aims to more accurately estimate toner supply timing by clearing, when a toner cartridge has been exchanged, the total sum of pulses of a laser pulse signal, then summing up pulses of the laser pulse signal each time an image is formed, thereby calculating the amount of toner in the toner cartridge.
To satisfy the aim, an image forming apparatus according to the invention comprises: a laser pulse arithmetic circuit configured to count a time period in which a laser pulse signal is in an ON state; a temperature sensor configured to monitor temperature in a developing unit and output temperature data; a humidity sensor configured to monitor humidity in the developing unit and output humidity data; a control section configured to calculate consumption of toner in the developing unit on the basis of a counted value of the laser pulse arithmetic circuit, temperature data obtained from the temperature sensor and humidity data obtained from the humidity sensor, thereby calculating a toner supply time period to maintain a constant toner amount in the developing unit; and a toner supply section configured to supply toner into the developing unit on the basis of the toner supply time period calculated by the control section.
Further, an image forming apparatus according to the invention, comprises: a scanner section configured to read image information on a to-be-copied object and create an image signal; an image forming section configured to form an image corresponding to the image signal output from the scanner section; a laser pulse arithmetic circuit configured to count a time period in which a laser pulse signal is in an ON state; a temperature sensor configured to monitor temperature in a developing unit and output temperature data; a humidity sensor configured to monitor humidity in the developing unit and output humidity data; a control section configured to calculate consumption of toner in the developing unit on the basis of a counted value of the laser pulse arithmetic circuit, temperature data obtained from the temperature sensor and humidity data obtained from the humidity sensor, thereby calculating a toner supply time period to maintain a constant toner amount in the developing unit, and clearing the ON-state time period of the laser pulse signal counted by the laser pulse arithmetic circuit when a toner cartridge has been exchanged; an F-ROM configured to store data related to the consumption of toner; a toner supply section configured to supply toner into the developing unit on the basis of the toner supply time period calculated by the control section; and an operation panel configured to display a message that the toner cartridge should be exchanged.
Furthermore, a control method for an image forming apparatus according to the invention comprises the steps of: counting a time period in which a laser pulse signal is in an ON state; monitoring a temperature in a developing unit and outputting temperature data; monitoring humidity in a developing unit and outputting humidity data; calculating consumption of toner in the developing unit on the basis of the counted value, the temperature data and the humidity data, thereby calculating a toner supply time period to maintain a constant toner amount in the developing unit; and supplying toner into the developing unit on the basis of the calculated toner supply time period.
Yet further, a control method for an image forming apparatus according to the invention comprises the steps of: reading image information on a to-be-copied object and creating an image signal, using a scanner section; forming an image corresponding to the image signal output from the scanner section, using an image forming section; counting a time period in which a laser pulse signal is in an ON state, using a laser pulse arithmetic circuit; monitoring a temperature in a developing unit and outputting temperature data, using a temperature sensor; monitoring humidity in a developing unit and outputting humidity data, using a humidity sensor; calculating consumption of toner in the developing unit on the basis of the counted value of the laser pulse arithmetic circuit, the temperature data of the temperature sensor, and the humidity data of the humidity sensor, thereby calculating a toner supply time period to maintain a constant toner amount in the developing unit, and clearing the counted ON state time period of the laser pulse signal when a toner cartridge has been exchanged, using a control section; storing data related to the consumption of toner in an F-ROM; supplying toner into the developing unit on the basis of the calculated toner supply time period, using a toner supply section; and displaying a message that the toner cartridge should be exchanged, using an operation panel.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.